Conjecture: Feedback doesn’t Help Much



Consider the additive Gaussian noise channel with stationary timedependent noise
$$Y (k) = X (k) + Z (k)$$
, where {Z(k)} has power spectral density N(f). A (2nR, n) feedback code for such a channel is given by a collection of functions
$$x_k^{(n)} (W, Y_1,Y_2, \dots, Y_{k-1})$$
$$k = 1,2, \dots, n, \; W \in \{1,2, \dots, 2^nR\}$$
and a decoding function
$$g^{(n)} \: R^n \rightarrow\{1,2, \dots, 2^{nR}\}$$


  1. 1.
    P. M. Ebert, “The Capacity of the Gaussian Channel with Feedback,” BSTJ, pp. 1705–1712 (Oct. 1970).Google Scholar
  2. 2.
    S. Pombra and T. Cover, “Gaussian Feedback Capacity,” to be submitted to IEEE Trans. Inf. Theory.Google Scholar

Copyright information

© Springer-Verlag New York Inc. 1987

Authors and Affiliations

  1. 1.Departments of Electrical Engineering and StatisticsStanford UniversityStanfordUSA

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